CVE-2026-77937 Letta through 0.16.8 Cross-Tenant Impersonation via user_id Header
High 8.6
Published
Updated
Check this codebase for CVE-2026-77937 and fix it if it is affected.
What it is: CVE-2026-77937 is a high-severity vulnerability in letta-ai letta, published on 20 Oct 2026.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77937 exists.
Affected product: letta-ai letta. No package-level version data is available, so check the vendor advisory linked from the reference page.
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-77937/ (Markdown: https://insights.sbomify.com/CVE-2026-77937/index.md)
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-77937?
CVE-2026-77937 is a high-severity vulnerability in letta-ai letta, published on 20 Oct 2026.
Official description
Letta through 0.16.8 contains an authentication bypass vulnerability that allows API callers to impersonate other users by supplying a self-asserted user_id HTTP header. Attackers can set user_id to another tenant's ID, even with LETTA_SERVER_SECURE enabled, to read and modify that user's agents, memory and configuration.
Weakness: CWE-639
Which versions are affected by CVE-2026-77937?
How do I fix CVE-2026-77937?
No fix has been published for CVE-2026-77937 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-77937 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77937 exists.
Sources
Also known as GHSA-8p6h-849r-ww4h.